The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Substrate processing systems are typically used to pattern, deposit, etch and ash various types of film on a substrate such as a semiconductor wafer. The substrate processing systems typically include a processing chamber with a substrate support such as a pedestal, an electrostatic chuck, a plate, etc. A substrate such as a semiconductor wafer may be arranged on the substrate support.
In chemical vapor deposition (CVD) or atomic layer deposition (ALD) processes, a gas mixture including one or more precursors may be introduced into the processing chamber to deposit a film on the substrate. In some substrate processing systems, radio frequency (RF) plasma may be used to activate chemical reactions. The RF plasma may be delivered remotely to the processing chamber through a gas distribution device or created directly in the processing chamber.
For example during processing, a photoresist layer may be used to define features in the film. Afterwards, the photoresist layer is typically removed. Ashing may be used to remove the photoresist layer. Ashing may be performed using a remote plasma source. The remote plasma source typically generates the plasma by exciting a reactive gas such as oxygen or fluorine using a radio frequency or microwave signal.
A gas distribution device such as a showerhead may be arranged between the remote plasma source and the substrate. The showerhead may include a plate made of aluminum that includes a plurality of holes defining a hole pattern. The hole pattern in the plate may extend approximately to an edge of the underlying substrate. The holes act as an ion filter. During use, heat in the plate tends to increase due to recombination of ions in the holes.
As the substrates increase in size and area, the amount of RF power supplied by the remote plasma source typically needs to increase to maintain a desired ash rate for the larger substrate. At the higher RF power levels, heating of the plate increases to an unacceptable temperature. While brazed showerhead designs allow water cooling to lower the temperature of the plate, they tend to have relatively low reliability. Gun drilled showerhead designs also allow water cooling to lower the temperature of the plate but are costly to manufacture.